com.itextpdf.kernel.pdf.canvas.parser.listener

Class FilteredEventListener

java.lang.Object

com.itextpdf.kernel.pdf.canvas.parser.listener.FilteredEventListener

All Implemented Interfaces:

IEventListener

Direct Known Subclasses:

FilteredTextEventListener

public class FilteredEventListener
extends Object
implements IEventListener

An event listener which filters events on the fly before passing them on to the delegate.

Field Summary

Fields

Modifier and Type	Field and Description
protected List<IEventListener>	delegates
protected List<IEventFilter[]>	filters

Constructor Summary

Constructors

Constructor and Description
FilteredEventListener() Constructs a FilteredEventListener empty instance.
FilteredEventListener(IEventListener delegate, IEventFilter... filterSet) Constructs a FilteredEventListener instance with one delegate.

Method Summary

Modifier and Type	Method and Description
<T extends IEventListener> T	attachEventListener(T delegate, IEventFilter... filterSet) Attaches another IEventListener delegate with its filters.
void	eventOccurred(IEventData data, EventType type) Called when some event occurs during parsing a content stream.
Set<EventType>	getSupportedEvents() Provides the set of event types this listener supports.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

delegates

protected final List<IEventListener> delegates

filters

protected final List<IEventFilter[]> filters

Constructor Detail

FilteredEventListener

public FilteredEventListener()

Constructs a FilteredEventListener empty instance. Use attachEventListener(IEventListener, IEventFilter...) to add an event listener along with its filters.

FilteredEventListener

public FilteredEventListener(IEventListener delegate,
                             IEventFilter... filterSet)

Constructs a FilteredEventListener instance with one delegate. Use attachEventListener(IEventListener, IEventFilter...) to add more IEventListener delegates along with their filters.

Parameters:

delegate - a delegate that fill be called when all the corresponding filters for an event pass

filterSet - filters attached to the delegate that will be tested before passing an event on to the delegate

Method Detail

attachEventListener

public <T extends IEventListener> T attachEventListener(T delegate,
                                                        IEventFilter... filterSet)

Attaches another IEventListener delegate with its filters. When all the filters attached to the delegate for an event accept the event, the event will be passed on to the delegate. You can attach multiple delegates to this FilteredEventListener instance. The content stream will be parsed just once, so it is better for performance than creating multiple FilteredEventListener instances and parsing the content stream multiple times. This is useful, for instance, when you want to extract content from multiple regions of a page.

Parameters:

delegate - a delegate that fill be called when all the corresponding filters for an event pass

filterSet - filters attached to the delegate that will be tested before passing an event on to the delegate

Returns:

delegate that has been passed to the method, used for convenient call chaining

eventOccurred

public void eventOccurred(IEventData data,
                          EventType type)

Description copied from interface: IEventListener

Called when some event occurs during parsing a content stream.

Specified by:

eventOccurred in interface IEventListener

Parameters:

data - Combines the data required for processing corresponding event type.

type - Event type.

getSupportedEvents

public Set<EventType> getSupportedEvents()

Description copied from interface: IEventListener

Provides the set of event types this listener supports. Returns null if all possible event types are supported.

Specified by:

getSupportedEvents in interface IEventListener

Returns:

Set of event types supported by this listener or null if all possible event types are supported.